dma-direct: provide page based alloc/free helpers

Some architectures support remapping highmem into DMA coherent
allocations.  To use the common code for them we need variants of
dma_direct_{alloc,free}_pages that do not use kernel virtual addresses.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>

diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h
index 9e66bfe369aa057ac9d285d1f3cede42e54387cf..61b78f934f6498dfe2bac7acf04ef8fb40d20094 100644 (file)
--- a/include/linux/dma-direct.h
+++ b/include/linux/dma-direct.h
@@ -67,6 +67,9 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
                dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs);
 void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
                dma_addr_t dma_addr, unsigned long attrs);
+struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
+               dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs);
+void __dma_direct_free_pages(struct device *dev, size_t size, struct page *page);
 dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
                unsigned long offset, size_t size, enum dma_data_direction dir,
                unsigned long attrs);

diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 22a12ab5a5e9aaac7ac5207d70b059bd75e48965..680287779b0ad2932187e9b1d400c7f9650b9652 100644 (file)
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -103,14 +103,13 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
                        min_not_zero(dev->coherent_dma_mask, dev->bus_dma_mask);
 }
 
-void *dma_direct_alloc_pages(struct device *dev, size_t size,
+struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
                dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
 {
        unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
        int page_order = get_order(size);
        struct page *page = NULL;
        u64 phys_mask;
-       void *ret;
 
        if (attrs & DMA_ATTR_NO_WARN)
                gfp |= __GFP_NOWARN;
@@ -150,11 +149,22 @@ again:
                }
        }
 
+       return page;
+}
+
+void *dma_direct_alloc_pages(struct device *dev, size_t size,
+               dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
+{
+       struct page *page;
+       void *ret;
+
+       page = __dma_direct_alloc_pages(dev, size, dma_handle, gfp, attrs);
        if (!page)
                return NULL;
+
        ret = page_address(page);
        if (force_dma_unencrypted()) {
-               set_memory_decrypted((unsigned long)ret, 1 << page_order);
+               set_memory_decrypted((unsigned long)ret, 1 << get_order(size));
                *dma_handle = __phys_to_dma(dev, page_to_phys(page));
        } else {
                *dma_handle = phys_to_dma(dev, page_to_phys(page));
@@ -163,20 +173,22 @@ again:
        return ret;
 }
 
-/*
- * NOTE: this function must never look at the dma_addr argument, because we want
- * to be able to use it as a helper for iommu implementations as well.
- */
+void __dma_direct_free_pages(struct device *dev, size_t size, struct page *page)
+{
+       unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
+
+       if (!dma_release_from_contiguous(dev, page, count))
+               __free_pages(page, get_order(size));
+}
+
 void dma_direct_free_pages(struct device *dev, size_t size, void *cpu_addr,
                dma_addr_t dma_addr, unsigned long attrs)
 {
-       unsigned int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
        unsigned int page_order = get_order(size);
 
        if (force_dma_unencrypted())
                set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
-       if (!dma_release_from_contiguous(dev, virt_to_page(cpu_addr), count))
-               free_pages((unsigned long)cpu_addr, page_order);
+       __dma_direct_free_pages(dev, size, virt_to_page(cpu_addr));
 }
 
 void *dma_direct_alloc(struct device *dev, size_t size,